1. Field of the Invention
The present invention generally relates to automobile grilles positioned at the front end of an automobile. More specifically, this invention relates to a flexible automobile grille which is compliantly mounted directly to the automobile's engine hood, wherein a number of resilient supports are utilized to provide rigidity to the grille while permitting flexure of the grille relative to the engine hood. The grille of this invention is particularly well suited for use with impact-absorbing bumpers which automatically rebound from a frontal impact.
2. Description of the Prior Art
Automobile grilles have generally evolved from what once was primarily a protective barrier, to its present status as primarily a decorative feature, though also often serving as the primary source of ventilation to the automobile's radiator. Accordingly, early grilles were formed from metal so as to have adequate strength to deflect objects from hitting the radiator. Today, the role of the automobile grille as a barrier has been largely supplanted by modern practices which position the radiator such that it is protected by other means. However, for styling purposes, the automobile grille is still present on most modern automobiles, though generally formed from plastic for lighter weight.
With the advent of energy- or impact-absorbing bumpers, automobile grilles have been required to undergo significant design changes in order to accommodate the stroke of the bumper, which can be as much as 3 to 4 inches. Current grille designs have primarily taught three solutions to this problem. The first and traditional solution is to position the grille entirely out of the path of the bumper during recoil after impact. This approach generally entails placing the automobile grille rearward of the bumper, resulting in an extremely square-looking profile which has little appeal according to modern design trends. In addition, such a design is not aerodynamic, and as such this approach is not generally followed, particularly as fuel efficiency becomes increasingly important. A second solution is to completely eliminate the grille, which generally entails sweeping the engine hood down such that it is suspended just above the bumper line. However, this approach has not been widely adopted in that it has rather limited styling appeal.
A third solution is to require the grille to be displaceable such that it can pivot or otherwise move out of the bumper's path during impact. Preferably, this approach allows the grille to be mounted flush with the surrounding hood, front end, body panels, and bumper so as to enhance the styling effect and aerodynamics of the automobile. Such an approach is illustrated by U.S. Pat. No. 3,792,889 to Fuener et al. There, a sequentially moving grille is taught in which the lower edge of the grille is pivotally secured to the automobile body while the upper edge of the grille is allowed to rotate about the lower edge. During impact, the rearward travel of the bumper forces the grille to pivot rearwardly about the grille's lower edge and against a spring element. Another example of the third approach is taught by U.S. Pat. No. 4,753,468 to Szymczak et al., which provides a pivot arm which pivots the grille rearwardly and upwardly during impact. Yet another example is shown in U.S. Pat. No. 4,834,436 to Nguyen, which substantially eliminates the arcuate displacement of the grilles of both Fuener et al. and Szymczak et al. by employing a four-bar linkage that displaces the grille in an entirely rearward manner during impact. U.S. Pat. No. 4,944,540 to Mansoor et al. also seeks to avoid an arcuate path by the grille during impact by a pin and slot arrangement having a return spring.
As can be readily appreciated by those skilled in the art, the above examples corresponding to the third solution all entail additional hardware and space to accommodate the displacement of the grille. In addition, the added hardware is also necessary to adequately support the grille so as to be able to withstand wind resistance and road vibration while the vehicle is in use. But the additional hardware requirement itself is a disadvantage when it comes to both costs and weight from the standpoint of the vehicle manufacturer. The added costs entailed in purchasing and installing the above required hardware to achieve the desired results will generally be significant, while the additional weight adversely affects the performance and fuel economy of the vehicle. Both considerations are of primary importance in the highly competitive automobile market.
An approach which tends to avoid the problems noted above is illustrated in U.S. Pat. No. 2,578,068 to Johnson. Johnson teaches a resilient grille and bumper combination which is resiliently attached at its lower edge to the automobile's frame. A more modern version of this approach is illustrated by U.S. Pat. No. 4,917,203 to Sacco et al. There, a grille is disclosed which is supported within a U-shaped radiator cover. The radiator cover is secured to and suspended from the engine hood by a pair of resilient inner plates which allow the radiator cover to elastically deflect when the bumper is impacted. An advantage to the above structure is that the added hardware and weight associated with the teachings of Fuener et al., Szymczak et al., Nguyen, and Mansoor et al. are avoided. In addition, Sacco et al. particularly illustrate the styling and aerodynamic benefits to the automobile when the grille is mounted flush with the surrounding body panels and bumper. However, the grille taught by Sacco et al. has a significant disadvantage, in that the resilient inner plates provide minimal support for the radiator cover. As a result, the radiator cover taught by Sacco et al. is highly susceptible to wind and road vibrations, and is likely to feel flimsy when handled while opening or closing the engine hood.
As a solution to each of the above shortcomings, U.S. Pat. No. 5,205,597 to Chase, assigned to the assignee of this invention, teaches an automobile grille which has the advantages of being able to deflect with the bumper during impact, yet is sufficiently supported by the automobile body so as to be able to resist road and aerodynamically-induced vibrations without requiring added hardware and weight. The solution taught by Chase involves varying the section modulus of a portion of the grille's structure to provide a mode of resiliency, thereby enabling the grille to absorb an impact with the bumper while still being securely attached along its periphery to the automobile body. Chase teaches a grille formed entirely from a resilient impact-resistant material, such as a high impact plastic, having a yield strength which is sufficient to endure the amount of deflection required to deflect with the bumper's stroke.
While the solution taught by Chase enables the automobile grille to flex significantly without sustaining permanent damage, some applications require that an automobile grille be capable of being stroked in excess of that possible with the grille taught by Chase. With such applications, the degree to which a grille must be capable of being stroked necessitates minimal support of the grille, which is detrimental to the stability and rigidity of the grille, as noted previously with the radiator cover taught by Sacco et al. In view of the prior art noted above, it would be expected that a grille constructed in accordance with the teachings of Johnson and Sacco et al., and having a greater stroke capability than that of Chase, would be highly susceptible to road and aerodynamically-induced vibrations, and feel flimsy when being handled while the engine's hood is being opened and closed.
Accordingly, what is needed is a flexible automobile grille which is particularly suited for use with impact-absorbing bumpers that automatically rebound from a frontal impact, wherein the grille is capable of sustaining significantly greater impacts than that made possible by Chase, yet is characterized by sufficient stability and rigidity so as to make the grille relatively unsusceptible to road and aerodynamically-induced vibrations, and amenable to physical handling during opening and closing of the engine hood.